Road equipped with road safety barriers fixed to the ground and installation method thereof

ABSTRACT

The present invention relates to the installation of road safety barriers also known as “guardrails”; and indicates a real “road system”, including special safety barriers, in which each trait of the safety barrier can be installed with the reasonable certainty of compliance with the required safety requirements, and these requirements can be defined differently depending on the trait. 
     Furthermore, this “road system”, including special safety barriers, is associated with an innovative installation and maintenance method, which is not significantly more expensive than the methods currently practiced for the installation and maintenance of simple road barriers, in which the fixing of the uprights to the ground is done by simple infixion into the ground using a “pile-driving machine”. 
     The invention is characterized by an appropriate ground fixing system, which is integrated in said “guardrail”.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The field of application of this invention concerns the installation ofroad safety barriers (hereinafter also referred to as “guardrails”).

Said barriers are an essential element in ensuring road safety. In fact,in addition to clearly delimiting the edge of the road, they areintended to significantly reduce the consequences of accidents involvingvehicles leaving the road.

2. Brief Description of the Prior Art

-   -   The main function of a “guardrail” is to ensure adequate safety        standards. For this reason, the so-called “guardrails” are        normally subjected to compliance with adequate mechanical        standards which, only after having been certified through real        tests (hereinafter also called “crash-tests”) with a vehicle,        allow to consider them compliant with the norm. It should be        noted that a correct interpretation of the standard should not        concern just the safety barrier as such, but also its        installation: in essence, although the road barrier        manufacturers provide their certified barriers, what really        guarantees the road safety is not just the barrier, but the        entire system consisting of the road and the barrier (as        installed).

Specifically, a “guardrail” must prevent vehicles from exit the road andtheir overturning, to avoid dangerous collisions with other vehiclesand/or elements outside the road. At the same time, it must be able toabsorb and dissipate all, or part of, the kinetic energy possessed bythe vehicle at the moment of impact, reducing, in a controlled way, thedecelerations induced by the collision to the occupants of the vehicle,and allowing its gradual return to the carriageway by stopping itstravel, possibly near the roadside. These behaviors of the “guardrail”can be achieved in different ways, focusing on the stability of theinstallation, providing that the uprights of the “guardrail” deform, butdo not detach from the ground, or also providing that some of theseuprights detach from the ground. These different strategies may dependon the terrain on which the “guardrail” is installed, but also on therequired safety requirements: it is clear that a road located on theedge of a precipice or on the embankment of a watercourse should favorthe objective of preventing off-road exits, while a road with free landon the sides can be safer if vehicles affected by an accident areallowed to stop their run off the carriageway.

Therefore, the real safety requirements and, consequently, the rulesthat should guarantee these requirements, can be respected in many ways:what must be assessed is the overall result, which has to do with thesafety of a road as a whole, equipped with appropriate safety barriers.

-   -   The combination of mechanical robustness (aimed at containing        the vehicle), the elastic-plastic deformability (aimed at        reducing the decelerations induced by the impact, by controlling        the dissipation of kinetic energy) and the breaking, or        detachment, of some elements of the “guardrail”, sets a        significant and not a simple technical problem for the        construction and installation of these road safety barriers.

The common practice, based on the known technique, does not adequatelyconsider these aspects concerning safety, and it is frequent that, inthe event of an accident, the authority which is responsible of themanagement of the road is responsible also for the consequences of thisaccident.

It is quite frequent that the “guardrails” installed along the roads donot normally meet the technical safety requirements, because theirinstallation does not reflect the certification conditions, with seriousrisk for the consequences of any accidents.

After all, the huge variety of installation conditions makes it verydifficult to build roads in which the installation conditions of the“guardrail” are homogeneous.

In summary, it can be stated that the known technique is satisfactoryfrom the point of view of the materials and elements that are used forthe realization of the “guardrail” as a stand-alone product, (intendedas a system certified by authorized laboratories), while it stillremains substantially unresolved the aspect concerning its installation,which often does not replicate the certification conditions of the“crash-tests”.

In conclusion, a good number of installed “guardrails” do not meet thereal safety requirements, due to installation differences.

A typical situation in which the installation doesn't meet safetystandards is considered below, more in detail. This is the very commoncase in which the uprights of a “guardrail” are planted into the groundby a maneuver performed with a so-called “pile driver”. This maneuverconsists in vertically positioning the upright of the “guardrail” at thepoint where it must be driven into the ground, after which, with amechanically operated hammer, it is beaten and driven into the ground(normally at a depth more or less equivalent to the part emerging fromthe ground).

This technique has its main advantage in the speed and simplicity ofinstallation. The upright has a very linear structure consisting of apiece normally with a constant profile in the buried part.

On the other hand, the tightness of the installation largely depends onthe compactness and characteristics of the ground that, if notparticularly compact, modifies the behavior of the road barrier in theevent of a vehicle collision: in this case, in fact, being the uprightsnot well stable in the ground, following the impact of vehicles, theywill tend to rotate rigidly in the ground, instead of flexing, reducingtheir deformation capacity and therefore the capacity to absorb anddissipate the necessary amount of kinetic energy; but, above all, theuprights fixed on the ground normally exhibit very different behaviorsdepending on the trait of road in which they are planted, withconsequent different performances with respect to the safety they canguarantee.

-   -   The known art proposes some solutions that aim to overcome this        problem related to the unevenness of installation, i.e. a        problem due to the installation of the “guardrails” on roads        whose edge is made up of soils whose compactness cannot be        controlled with the necessary accuracy.

Some solutions provide for the use of uprights whose part to be fixed tothe ground has an appropriate shape to ensure greater sealing, forexample by using uprights associated with an enlarged plate that makes agreater quantity of soil collaborate with the upright seal, when the“guardrail” is subjected to a violent impact caused by an accident.

These solutions based on the use of uprights, whose shape of the buriedpart, has an appropriate shape, make the seal more secure, but do notsolve the problem of installation unevenness; they also provideparticularly improved performance only when the ground is compact; andthey end up to produce an almost negligible effect precisely in thecases in which such improved performance would be needed most, i.e. ininstallations on less compact ground.

More interesting are the solutions that involve the use of anchors thatgrip the ground below the road surface.

The interest derives from the fact that the ground under the roadsurface is normally compacted in order to avoid the subsidence of theroadway due to the weight of the vehicles in transit. It is evident thatsuch an inconvenience (i.e. the subsidence of the roadway) must beabsolutely avoided, and therefore the surface on which the roads arebuilt is always suitably prepared and, in particular, is pressed so asto make it very compact.

A solution of this type is taught in the patent application n.PCT/162019/050262-“Reinforcement element for fixing at the base, inground, the uprights of roadside safety barriers” (by the same authorsof the present patent application), which describes an uprightconnected, through a connecting element which works in tension, to oneor more plates buried under the road surface. This solution, in itsgenerality, is conceptually quite simple, but in its actualimplementation it poses a series of problems, and requires furtherrefinements, both to solve some installation problems, and to achieve areal quantitative control of the performance of the “guardrail”, as asystem, in the event of an accident. Another solution, which is based onthe exploitation of the greater compactness of the ground under theroadway, is taught in WO 2019/008525 A1-“Device for anchoring safetyroad barriers poles to the ground”. This is a solution that provides fora helical element, the cost of which is presumably very significantcompared to the cost of the other elements of the “guardrail”; thiselement is suitable for being inserted into the ground by means of ascrewing maneuver. Also this solution presents the problems of theprevious one and, in addition, requires specific instrumentation for theinstallation, making the installation costs even more onerous, since itcannot be carried out with the instrumentation normally supplied tocompanies operating in the sector.

Furthermore, the anchoring system taught in WO 2019/008525 A1, in caseswhere it is most needed (i.e. when the roadside is not very compact, anddoes not offer adequate resistance), must penetrate deep enough into theground below the roadway, in a zone that is often occupied byunderground services. It is definitely preferable that the “road system”as a whole, including the appropriately installed safety barriers, doesnot invade the ground below the road substrate (approximately up to adepth of the order of one meter): this in order to decouple, as much aspossible, the management of underground services (often associated withroad layouts) from the road management.

-   -   A further problem, currently largely neglected, consists in        having road barriers whose behavior can be controlled according        to the trait of road.

In fact, there are sections of road where the priority objective of asafety barrier is to avoid going off the road: for example, due to thepresence of a precipice, or a watercourse, or to protect what there isoutside the street itself. In other sections, however, it is preferablethat the vehicles involved in an accident go off the road, and whatmatters most is that their kinetic energy is dissipated, avoidingviolent crashes against the barrier itself.

In fact, there are different types of road barriers, characterized byresistance parameters that allow them to be classified according to thebehavior they must assume during accidents, defining the forces theymust resist before bending or breaking; but there are no barriers wherethese parameters can be easily adjusted even during installation.Normally, a certain type of barrier, defined by the project, isinstalled in long stretches of road without variations, and thediversity of behavior depends only on the ground on which theinstallation takes place.

In other words, variable performances are obtained in a substantiallyrandom way, without the possibility to exercise a real control of theperformances that this barrier should guarantee, so that they dependonly (as it should be) on the real security needs that are required inthe different road traits.

-   -   Ultimately, it can be said that the current “guardrail”        technology suffers from the fact that the “guardrail” is        conceived as an accessory, made independently by a specialized        manufacturer, which serves to guarantee the safety of a road,        built and managed from another subject. Instead, it would be        more correct to directly conceive a road as an overall system,        equipped with its own safety barrier, when it is necessary or        foreseen. In fact, the effectiveness of a barrier is closely        linked to the ground on which it is installed.

It is observed that the treatment and preparation of the ground where aroad is built is part of the construction process of the road itself:indeed, it is one of the most important phases of road construction. Awell-made substrate guarantees the durability and integrity of a roadperhaps more than the laying of the surface, which, in any case, is anoperation for which a periodic refurbishment must be envisaged formaintenance purposes; while the preparation of the substrate is a jobthat must be done at the beginning, once and for all.

Among the known art documents, which are considered somehow relevant forthe purposes of the invention described below, it's worth mentioningalso WO 2020/157074 A1 (“Road restraint system with elements foranchorages of the poles to improve performance”—Bruni M. et al. [IT]-6Aug. 2020).

SUMMARY OF THE INVENTION

-   -   The main purpose of the present invention, therefore, is to        indicate a real “road system”, including appropriate safety        barriers, in which each section of the safety barrier can be        installed with reasonable certainty of compliance with the        required safety requirements, given that these requirements can        be defined in a different way according to the case.

In addition, these safety requirements must be able to be defined evenduring construction, without necessarily requiring a detailed design ofsafety barriers for the entire length of a road.

In particular, the safety barrier indicated in the invention must beable to be installed in such a way as to react both through plasticdeformations, and through programmed breakages of some elements, beingsuch reactions decided during the installation operation.

It is clear that the control of some mechanical requirements duringinstallation cannot be based on the installation of different barriersdepending on the requirements to be obtained, because this solutionwould pose substantial problems when ordering the materials; Instead, itis desirable to have a single barrier, which has suitable adjustmentelements to allow the control of mechanical requirements.

-   -   Furthermore, another purpose of the present invention is to        indicate a “road system”, including special safety barriers, in        which the installation of the barriers is as easy as possible,        even if some elements require installation in the compact ground        of the road substrate, under the asphalt surface.

The installation must be able to be carried out with instrumentstypically supplied to operators in the sector, without requiring them tobe equipped with specific equipment, built specifically for a particulartype of “guardrail”. Typical equipment allowed are the so-called “piledriving machines”, tools for cutting asphalt and the equipment necessaryfor sealing cracks in the asphalt.

-   -   Finally, the present invention must also pay great attention to        maintenance aspects, so that the replacement of parts of the        “guardrail” are also efficient, both in the context of normal        maintenance, and in contexts following accidents, when the        “guardrail” is inevitably damaged.

Still in the context of maintenance, it should be noted that theinstallation of road barriers that require the positioning of someelements under the road surface should not interfere (in a problematicway) with the routine maintenance of the road surface itself.

In general, the “road system”, including special safety barriers, mustbe associated with an innovative method of installation and maintenance,which is not significantly more onerous than the methods currentlypracticed for the installation and maintenance of simple road barriers,in which the fixing of the uprights to the ground takes place simply bydriving them into the ground through the use of a “pile driver”.

These objectives are achievable in a “road system” which includes a roadwith a stabilized road substrate on which a road surface is laid, thatis a road with a road substrate consisting of ground with knowncompactness characteristics; and said road is equipped with a roadsafety barrier comprising a plurality of uprights, infixed in theroadside as in the known art; moreover, said road is characterized inthat said safety barrier comprises, in turn, at least the elementslisted below.

-   -   A vertical plate system, with a thin section, infixed in said        road substrate below the road surface, typically consisting of a        layer of asphalt;        -   in the preferred embodiment, said vertical plate system has            a cross-shaped section.    -   A junction element designed to be coupled to the uprights of a        road safety barrier by wrapping them around the base.    -   A connecting tie rod laid, or slightly buried, on the road        substrate, which is        -   coupled to said vertical plate system at one of its ends,            and        -   releasably coupled to said junction element at its other            end.

And said junction element comprises parts with programmed breakage suchthat said junction element breaks when said connecting tie exerts atraction force higher than a predetermined threshold, and lower than theforce that would damage said connecting tie rod or the force that wouldproduce a displacement of said vertical plate system with respect to theroad substrate in which it is infixed, and when said junction elementbreaks, said “guardrail” upright is no longer connected to said verticalplate system.

This “road system”, including special safety barriers, is suitable forbeing built even when the road, without a safety barrier, is already inplace and the asphalt surface is already laid over the roadway, using amethod of installing a road safety barrier as described above; and suchinstallation method includes at least the steps listed below.

-   -   Cutting of the asphalt        -   a. according to the section shape of the plate system,        -   b. according to a line that connects the previous cut and            the position where the installation of a “guardrail” upright            is planned.    -   Hooking of said tie rod to the plate system and laying it inside        the cut referred to in the above point “b.”, so that once        installed, said tie rod is laid on the road substrate (or        slightly buried) below the road surface level.    -   Driving the plate system with a pile-driving machine, so that        the latter is substantially buried entirely in the road        substrate or protrudes from it for a very small stretch compared        to the thickness of the road surface above.    -   If the upright for the “guardrail” is already infixed        -   ✓ coupling the junction element to the upright for            “guardrail”,        -   ✓ coupling the junction element to the end of the tie rod            which is located near the upright for “guardrail”,        -   ✓ tensioning the tie rod by means of a special maneuver on            the junction element.    -   If the upright for the “guardrail” is not already infixed        -   ✓ coupling the junction element to the end of the tie rod            which is located near the point where the upright for            “guardrail” must be infixed,        -   ✓ driving into the ground the upright for “guardrail”, using            a pile driver so that said upright slips into the junction            element remaining hooked to it,        -   ✓ tensioning the tie rod by means of a special maneuver on            the junction element.    -   Sealing of the cuts made on the asphalt paving.    -   Note that both the plate system and the tie rod are buried in        the road substrate or protrude slightly above it. This expedient        allows the removal of the road surface for a possible remaking        without damaging either the plate system or the tie rod. These        latter elements, in fact, can have an extremely long life and,        in theory, do not need to be replaced even after an accident.

In fact, the elements that break first are always the junction elements,which are located near the uprights, and therefore on the roadside, in aposition of easy access.

BRIEF DESCRIPTION OF THE DRAWINGS

The main advantage of the present invention consists in the fact thatany upright for “guardrail” installed according to the teachings of thepresent invention satisfies all the main requirements for which it wasconceived, designed and certified.

Moreover, this invention also has further advantages, which will becomemore evident from the following description, from some examples ofpractical embodiments which illustrate further details, from theattached claims which form an integral part of the present description,and from the attached figures in which:

✓ FIGS. 1 a and 1 b show the main elements of a safety road barrier(“guardrail”);

✓ FIG. 2 shows a “guardrail” according to the known art, fixed to thebase by driving the uprights into the ground;

✓ FIG. 3 shows, in a simplified way, a perspective view of some detailsof an installation of an upright for “guardrail” according to theinvention;

✓ FIGS. 4 a and 4 b show two examples of implementation of a junctionelement in a “guardrail” system according to the invention;

✓ FIG. 5 shows, in a simplified way, a plan view of an installation ofsome uprights for “guardrails” according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 a shows a section of a typical road safety barrier (also called a“guardrail”). This barrier is seen from inside the road and, in general,it is composed of the elements listed below:

-   -   substantially vertical elements, normally called uprights, which        support the barrier itself, and indicated with the number 110        (also in the following figures);    -   a horizontal containment metal strip, indicated with the number        130 also called horizontal blockout bar;    -   an eventual upper beam, indicated with the number 140.

The uprights 110, in a typical and widespread installation method, arefixed to the base by driving them into the ground. The number 200indicates the land where the “guardrail” is installed, in the casesconsidered by the present invention.

-   -   FIG. 1 b represents the same “guardrail” shown in FIG. 1 a , but        it is seen in a section orthogonal to the direction of the road.

The numbers indicate the same elements as in FIG. 1 a . FIG. 1 b alsoallows viewing of a spacer element between the upright 110 and thehorizontal blockout bar 130. Said spacer element is indicated with thenumber 120, it has the main function of connecting the horizontalblockout bar 130 with the upright 110, and plays an important role indetermining the performance of the “guardrail” as a whole.

Another feature, which can be appreciated from the view of FIG. 1 b , isthe profile of the horizontal blockout bar 130. This profile is theresult of a long evolutionary process and has the advantage of ensuringan excellent compromise between mechanical performance and costs.

-   -   It has already been stated that the mechanical performance of        road safety barriers according to the prior art are satisfactory        when they can operate in nominal conditions, because only in        such conditions all the parts of the “guardrail system” (meaning        all its component parts briefly summarized with the help of FIG.        1 ) work according to the design specifications when an accident        occurs and the barrier is subjected to strong impacts. The        nominal conditions are those that correspond to the test        conditions during the so-called “crash-tests”.

There are various ways in which the performance of a “guardrail” can betested: ranging from tests carried out in the laboratory to real testsin which a true vehicle simulates an accident and hits the “guardrail”.The tests performed by simulations with real vehicles are certainly themost significant, as they clearly show whether the “guardrail” performsits main function, which is the containment of a vehicle that is gettingout of the road and stops its run in a point that minimizes thedangerous consequences of a simulated accident. This containmentfunction always requires the complete dissipation of the kinetic energyof the vehicle involved in the accident, and this dissipation can occurin many ways: through the plastic deformation of the “guardrail”, orthrough the breaking of parts thereof. In some cases it is required thatthe “guardrail” does not detach from the ground where it is installed,while in other cases, some uprights may also detach from the ground andthe containment takes place due to the holding of the horizontalblockout bar which remains attached to a plurality of uprights, some ofwhich, when stressed by an impact of a mass having a reduced momentum,do not detach from the ground.

Ultimately, the “optimal guardrail” is the one that performs itsfunction in the best possible way, and its behavior depends not only onthe “guardrail” as such, but also on the type of road and thecharacteristics of the ground on which it is fixed to the ground.Finally, in FIG. 1 b , above the ground 200 the road surface is alsorepresented, indicated with the number 210, which typically consists ofa layer of asphalt with a thickness of about ten centimeters.

-   -   FIG. 2 illustrates the behavior of a “guardrail” installed in        the ground on the road quay, as occurs in the vast majority of        real cases. In fact, in the majority of real installations the        uprights 110 of a “guardrail” are simply driven into the ground        200 without particular attention to the characteristics of this        ground 200. Therefore, when the “guardrail” is hit by an impact        force, indicated in FIG. 2 with the number 400, the stiffness of        the road quay is often modest, typically it is not sufficient to        keep vertical the upright 110, which does not deform and        typically rotates as indicated in FIG. 2 (in which the rotated        position of the upright 110 is represented with a dashed line).    -   FIG. 3 instead shows a detail of a road equipped with a safety        barrier according to the teachings of the invention. Differently        from FIG. 2 , in which the characteristics of the ground 200        were not substantially relevant (as they were not adequately        taken into account for the installation of the “guardrail”), the        ground is here depicted in greater detail. In fact, the number        201 indicates an area of land with characteristics different        from the generic soil 200. In fact, the roadway on which a road        is built, normally (practically always) undergoes a        stabilization treatment by compacting and pressing the terrain        on which the road surface is then spread. In fact, a so-called        road substrate (or roadbed) is always created, whose depth is of        the order of one meter (generally the roadbed is designed        according to the geological characteristics of the terrain on        which the road is built). Said road substrate 201 is essential,        and serves to prevent subsidence phenomena of the road when it        is loaded with the weight generated by vehicular traffic. Being        a treated terrain, said road substrate 201 has known compactness        characteristics, generally very good, because, as said, it is a        terrain which must not deform under the weight of the vehicles        passing on the road. Said road substrate 201 is obviously under        the road surface, always indicated with the number 210;        certainly, a part of terrain treated as the road substrate also        extends towards the roadside, but its characteristics along the        edges are certainly not as controlled as those below the road        surface, and they are somehow affected by the characteristics of        the surrounding terrain 200.

Another feature of the road substrate 201 is that (at least in roads atthe state-of-the-art) it is homogeneous and should not host the presenceof underground utilities (e.g. ducts or pipes) which should therefore belocated below it.

The road substrate 201 therefore represents the ideal ground foranchoring the uprights 110 for the installation of safety barriers.Anchors of this type are known, for example from patent application no.PCT/162019/050262-“Reinforcement element for fixing at the base, inground, the uprights of roadside safety barriers”, or from WO2019/008525 A1-“Device for anchoring safety road barriers poles to theground” (both already mentioned previously); however, in the knownsolutions some problems remain unsolved, such as the control of themechanical performance of the guardrail, and its consequent behavior inthe event of accidents, and the installation and maintenance problems,which are very onerous in the known solutions.

With reference to the mechanical performance, the trick taught in thepresent invention consists in the particular composition of theanchoring system, which must be composed of several parts, among whichat least the three parts listed below must be present:

-   -   1. a system of vertical plates, indicated with the number 153,    -   2. a connecting tie rod, indicated with the number 152,    -   3. a junction element, indicated by the number 151.

Said system of vertical plates 153 is designed to be infixed verticallyin the road substrate 201, where this is more compact, in an area belowthe road surface 210, possibly not too close to the edge of the road.

The infixion must take place so that its upper part remains near theupper limit of the road substrate 201 and does not cross it completelydownwards, so as to minimize the risk of breaking any undergroundservices during the infixion maneuver (remember that the undergroundservices are normally made to pass under the road substrate).Furthermore, they must not protrude excessively above the road substrate201, in order not to interfere with the remaking of the above roadsurface 210 which, from time to time, are carried out for the roadmaintenance.

Another characteristic of said system of vertical plates 153 (notclearly visible in FIG. 3 ) is that it is preferable that it has a thincross section or, in any case, a very small section surface. A preferredconformation of the section of said system of vertical plates 153 is across shape. This feature, as will also be clarified later, isfunctional to the optimization of installation and maintenanceoperations.

Said connecting tie rod 152 is an element which works in tension beingconnected to said system of vertical plates 153 on one side and to anupright 110 on the other, even if, as will be clarified below, theconnection with the upright 110 is not a direct connection. The functionof said connecting tie rod 152 is to hold the upright 110 to which it isconnected in the installation position, when the latter is stressed byan impact force, again indicated with the number 400, and coming fromthe road.

The junction between an upright 110 and a connecting tie rod 152, asalready mentioned, is not a direct junction: the teachings of thepresent invention provide that it is implemented through said junctionelement 151. The functions of said junction element 151 are more thanone: in fact, in addition to guaranteeing the junction between anupright 110 and a connecting tie rod 152, it allows to use uprights ofvery simple manufacture, such as those typically used in implementationsaccording to the known art, which can be installed by driving throughthe use of a pile-driving machine, and which do not require particularconformations to hook onto said connecting tie rod 152.

Furthermore, and this is perhaps the most important characteristic ofsaid junction element 151, it is an element of rather limited dimensionswhich is located near the base of the uprights 110, in an area notcovered by the road surface (so that the maintenance operations areeasy), and which can be sized to break when stressed by predeterminedforces.

Basically, said junction element 151 must break before said connectingtie rod 152 breaks and before said system of vertical plates 153 movesdue to a particularly high impact force 400 which, acting on the upright110 towards the outside the road could drag the whole system of verticalplates 153.

Not only that, the programmed breakage of said junction element 151 canbe decided, according to the case, so as to hold the upright 110 inposition to determining the deformation of the upright 110 at its base,or it can be sized to break before this deformation happens, letting thepost 110 rotate without deforming, or deforming only to a small extent.It is clear that when said junction element 151 is broken, theconnection between the vertical plate system 153 and the upright 110 isalso lost.

In short, it is possible to concentrate on said junction element 151,all the adjustments on the mechanical performances that are intended tobe obtained with regard to the behavior of a “guardrail” in the event ofan impact.

It is also emphasized that, in addition to regulating the mechanicalperformance of the “guardrail”, the use of a junction element 151, witha programmed and predetermined break, allows to preserve the integrityof the roadway in the event of particularly violent accidents thatinvolve heavy vehicles, avoiding that the impact forces may be such thatthe system of vertical plates 153 can be torn off the road substrate.

Said junction element 151 can be made according to many variations. Infact, it can be a simple horseshoe-shaped element that wraps the upright110 made with a thickness such as to give it the desired resistance, orit can be assembled with a higher resistance part completed with a lowerresistance bar, closed or hooked to the connecting tie rod 152, by meansof screws or pins with programmed break. In short, what is important isthat said junction element 151 wraps around the base of the upright 110and has a predefined strength, so that it breaks when a predeterminedstress is reached, or it never breaks before the upright is bend over.

FIG. 4 a shows an example of implementation of a junction elementaccording to the invention which has proved effective in the context ofsome “crash tests”. The junction element presented in FIG. 4 includes:

-   -   a U-shaped element, indicated with the number 151.1, whose size        is suitable for “wrapping” a “guardrail” upright;    -   a bar, indicated with the number 151.3, designed to close the        element 151.1 in the shape of a “U”, hooking onto its two ends;        and    -   a pair of screws, indicated with number 151.2, which are used to        fix said bar 151.3 to said element 151.1 in the shape of a “U”.

The junction element thus composed is very simple. Its shape allows theuse of normal uprights designed to be infixed in ground, which, when the“guardrail is installed, are inserted into the concavity of the” U″shaped element 151.1.

Bar 151.3 allows to install the overall system by wrapping the uprightsof the “guardrail” even if the “guardrail” itself is already assembled.Finally, the screws 151.2 allow you to close the junction element 151 asa whole.

In a variant very similar to that shown in FIG. 4 a , the screws can bereplaced by two nuts that are screwed onto the ends of the “U”-shapedelement 151.1, suitably threaded. In addition to the closing function ofthe junction element 151, these screws 151.2 (or the equivalent nuts)can also act as a mechanism for tensioning the connecting tie rod 152after installation.

As mentioned, an essential feature of said junction element 151 is givenby the fact that it must be able to split (thus opening the ring thatholds the base of the upright 110) by effect of a predetermined andcontrollable stress force.

The programmed break can be obtained by acting on the dimensioning ofthe thickness of the material with which said “U” shaped element 151.1is made, or by acting on the choice of screws 151.2, or on the tightnessof their thread.

The programmable break can also be adjusted in the field, and veryeasily, for example by making a hole on said bar 151.3 as shown in FIG.4 , where a hole indicated with the number 151.4 is visible. Evidently,in correspondence with the hole a weak point of said bar 151.3 isdetermined, which will break precisely in that zone when stressed by astrong traction which tends to widen said junction element 151; and theforce necessary to break will be less the larger the hole. In this way,by making holes of different sizes on the bar 151.3, it is possible toadjust the programmed breakage of the junction element 151. Furthermore,said junction element 151 is designed to hook to said connecting tie rod152 (shown in FIG. 3 ). Even this hooking arrangement can be obtained inmany ways: a very simple, even banal, way is to provide a hook on theend of the connecting tie rod 152, which hooks said junction element 151at any point.

FIG. 4 b shows another embodiment of the junction element 151, alsotested in experimental “crash tests”. FIG. 4 b shows said joiningelement 151 in an overall view in which it is connected to a connectingtie rod 152 (in a form of implementation consisting of two metal bands),and to a system of vertical plates 153 (also this last in a form ofimplementation other than that previously considered, which had a crossshaped section). The junction element 151 is then shown as an enlargeddetail in FIG. 4 b , to highlight its simplicity: it is essentiallyformed by a metal bar bent in a “U” shape, and does not require anyclosing bar, since the closure around the base of the upright to whichit is to be coupled is completed by the end of the connecting tie rod152.

Breakage can be controlled:

-   -   by acting on the dimensioning of the thickness of the metal bar        bent to “U”, of which the junction element 151 is made up;    -   or by choosing the mechanical strength of the screws with which        the junction element 151 is attached to the connecting tie rod        152;    -   finally, even in this form of implementation, weakened breakage        areas can be created by making holes or incisions on the “U”        bent metal bar, of which the junction element 151 is made.

Ultimately, the junction element 151 shown in FIGS. 4 a and 4 b reallyrepresents only few of the many forms of implementation with which itcan be implemented, provided that the few essential characteristicsrequired for the implementation of the present invention are preserved;and in particular, the possibility of making it so that it breaks, byopening, stressed by a predetermined force, that it is of reduced size,and that it is designed to be mounted at the base of the “guardrail”uprights in an easily accessible position for its installation,maintenance or replacement.

-   -   With the aid of FIG. 5 , it is possible to illustrate how the        present invention also offers a satisfactory solution to the        installation problem: allowing both installation and maintenance        in a relatively simple way, and above all with procedures that        can be performed with the typical machinery that is normally        supplied to operators involved with “guardrail” installations.

FIG. 5 shows, in a very simplified way, a road, indicated with thenumber 300, equipped with a safety barrier according to the teachings ofthe present invention. For reasons of essentiality, in FIG. 5 thebarrier is installed only on one side of the road, and the proportionsbetween the sections of the uprights and the road width are obviouslyunrealistic: however the purpose of the representation is only tosupport the description of the “road” as a whole, intended as a system,highlighting some problems concerning the installation of the safetybarrier on the roadside, and its possible maintenance. FIG. 5 shows fouruprights, indicated with the number 110, fixed on one side of the road300. It is observed that the uprights shown in FIG. 5 are of a verycommon type, with “C” profile, and, regardless of the profile, they areof the type that can be easily installed by infixing them on the ground,using a pile-driving machine.

Each of said uprights 110 is surrounded by a joining element 151.

Well inside the street 300, the shapes of the section of three systemsof vertical plates are highlighted, again indicated with the number 153.

Finally, each upright 110, through the junction element 151 and aconnecting tie rod 152 is connected to at least one system of verticalplates 153.

Although a simple connection scheme is practicable, in which eachupright 110 is connected to a single system of vertical plates 153, itcan be observed that there may be some convenience in connecting eachupright 110 to a pair, or even to three, vertical plate systems. In thisway, when an upright 110 is hit by an impact coming from inside theroad, and which would therefore tend to push the upright towards theoutside of the road itself, the resistance to this movement would beexerted not only by the resistance of a single system of vertical plates153, but by the strength of two, or three of these. In the example ofFIG. 5 , the vertical plate systems 153 are placed in an intermediateposition between two uprights 110, furthermore each upright 110 isconnected to the two vertical plate systems 153 which are located at itssides, as well as each system of vertical plates 153 is connected to thetwo uprights 110 which are at its sides. This connection scheme has theadvantage of being very simple and, in addition, it has the advantagethat, when two contiguous uprights are hit simultaneously by an impactthat would tend to move them away from the road, the two reaction forcesexerted on a system of vertical plates 153, and transmitted by the twoconnecting tie rods 152 connected to this vertical plate system 153,have a component that tends to cancel itself out, and therefore does notcontribute to a potential displacement of the vertical plate systemitself which, as explained, must remain stationary in its position evenin the event of an accident. It has to be recalled that each of theseconnections can be made as illustrated above, with the help of FIG. 3 .

Regardless of the connection scheme, which can be chained as shown inFIG. 5 , or organized in another way, giving rise, once again, to manyvariants of implementation, what is important to highlight is that thewhole system can be installed in very simple way. In particular, it isinteresting to note that even the installations of elements that are tobe positioned under the road surface 210 can be installed with relativeease.

In fact, an essential feature of the system of vertical plates 153 isthat it has a thin horizontal section, and this allows to drive saidsystem of vertical plates 153 into the road substrate, without removingthe asphalt of the road surface, but simply by cutting it according to ashape as that of the vertical plate system 153. In the case of theexample shown in FIG. 5 , the cross-sectional shape of the verticalplate system 153 is a cross shape, which represents one of the preferredimplementation forms for its effectiveness, and for its simplicity.

Once the correct shape has been cut, the system of vertical plates 153is driven into the road substrate by means of a pile-driving machinecommonly supplied to operators in the sector.

The connecting tie rod 151 also has a thin shape that allows it to beinserted under the road surface through a cut in it.

It is noted that the cutting of the road surface is a relatively simpleoperation, which does not require special tools (it is commonly foundamong the equipment supplied to operators in the sector, likepile-driving machines).

Among the road surface restoration operations, one of the simplest isprecisely the sealing of the cuts. Therefore, through this sealingoperation, the road surface is restored and made accessible so that theroad can be traveled.

The installation operations described above can also take place if thevertical plate system 153 has a section with enlargements (for examplein the center). In this case, in addition to cutting the asphalt, it isalso necessary to carry out a core drill to remove a small part of theroad surface in order to make a hole in the road surface itself, toaccommodate any enlargement of the vertical plate system 153. It is hereobserved that the core drilling of asphalt for the removal of smallasphalt layers is a simple operation and can be carried out with genericequipment, therefore there are no problems with respect to the generalobjectives of the invention which aim to seek a solution that can beimplemented by a large multitude operators without placing requirementson the instrumentation they must have at their disposal, posingpotential discrimination in the choice of operators to whom to assignthe work.

In this latter case, the restoration of the road surface is slightlymore complex, because we do not have to limit ourselves to sealing acut, but it is also necessary to plug the hole made with the coring;however, for small holes, even this maneuver is relatively simple andcan be performed with cold worked material.

It is clear that the restoration of the road surface is important toquickly restore the viability of the road 300, but, obviously, theasphalt paving remains marked by the interventions carried out. However,at the first maintenance of the asphalt resurfacing, every tracedisappears, and the buried underground system is designed to last overtime.

At this point, it is reiterated that both said vertical plate systems153 and said connecting tie rods 152, when installed, are in contactwith the road substrate 201 (the vertical plate system 153 is immersedin the road substrate), and possibly immersed only in a small part inthe bottom part of the road surface 210, so that even maintenance whichrequires the removal of the road surface, for the subsequentreconstruction, can be carried out without interfering with the systemdescribed.

Once the vertical plate systems 153 and the connecting tie rods 152 havebeen installed, the ends of the connecting tie rods 152 which are closeto the uprights 110 must be connected to the uprights themselves: asalready explained, this occurs through the junction elements 151.

From the installation point of view, it is important to observe how thiscoupling between the connecting tie rods 152 and the junction elements151 can take place indifferently even if the uprights 110 are installedor before installing them. In this second case, the junction elements151 are placed on the ground so that they surround the point where theupright 110 is to be infixed, and the latter can be driven in at a latertime, as normally occurs with a pile driver. The installation is thencompleted by tensioning the connecting tie rod: this maneuver can alsotake place with one of the many known tensioning systems, for examplewith a screw system positioned on the junction element.

This installation sequence, that is the fixing to the ground of theuprights 110 of the “guardrail” after the installation of the verticalplate systems 153 and the connecting tie rods 152, is typical of theinstallations carried out during the construction of new roads, in whichthe complete road, with its mantle, is normally completed before theinstallation of the “guardrails”: in this case it is obviouslyconvenient to install the vertical plate systems 153 and the connectingtie rods 152 as soon as the road substrate 201 is ready, before layingthe road surface 210 (thus avoiding unnecessary cuts).

On the other hand, when it is necessary to reinforce an existing safetybarrier, which is present on a complete road, the junction elements 151must be coupled to the already fixed uprights 110: for this reason it isnecessary that they are composed of several pieces that allow theiropening, to wrap the base of the uprights 110, and a subsequent closing,around the base of the uprights 110, ending with a tensioning operationof the connecting tie rods, obviously pre-installed as already explainedabove.

A final observation, about maintenance aspects, concerns the access tothe connecting tie rods 152, or to the vertical plate systems 153, whenthese elements are under a road surface 210, which has been redone afterthe installation of these elements, and therefore the signs of the cutsare not visible. Well, being the elements in question, in general, metalelements that are located at a depth of the order of ten centimeters, itis easy to find them using a metal detector, which is, for sure, able toidentify the precise position where to make a cut for reaching theelements to be maintained.

Concluding Remarks

In general, as seen from the previous description, the “road system”,according to the present invention, lends itself to numerousimplementation variants, as well as the method to implement it, can beput into practice with some variants, provided that the essential stepsindicated in the attached claims are maintained.

The provided description already highlights how many variations arepossible. In fact, the possible forms for making the vertical platesystems 153 are innumerable, as well as the junction elements 151 andthe connecting tie rods 152 can be implemented in many ways to connectthem to the uprights 110 for “guardrails”.

With strict reference to the geometric shape of said vertical platesystems 153, it is worth underlining how the plates can assume allpossible geometric shapes. All these variations of shape show that it isnot the shape of the plates that is a characterizing prerogative, butrather the fact that these plates are a functional element designed inorder to exploit a greater quantity of earth to increase the infixionstrength of an upright for “guardrail” 110, when hit by a violentimpact.

Regarding their shape, the only feature that seems recommendable is thatthey are flat, so that they can be driven into the road substrate 201 byinserting them into straight cuts and therefore easy to be done. It isevident that if these plates were obtained on wavy metal plates, thecutting of the road surface 210 to drive them into the road substrate201 should also have a wavy shape, causing a useless installationdifficulty.

Possible further variants may also depend on technological aspectsconcerning the individual components of the system, such as anyadditional consolidation and stiffening subsystems, but also on thematerials that can be used to make each single part of the system.

These variants can offer further advantages over those alreadymentioned, and can be implemented by the man skilled in the art withoutthereby departing from the scope of the invention as emerges from thepresent description and the attached claims.

Furthermore, the invention itself can be implemented in a minimal orsuperabundant way, for example with plate systems composed of a singleplate, or with a number of plates greater than two, and arranged invarious ways and in different directions: even if the solution with twoplates arranged in a cross (therefore with a four-branch system) appearsto be the preferred form of implementation for simplicity ofconstruction and installation (making two orthogonal cuts seems thesimplest thing to do).

1. A road with a stabilized road substrate (201) consisting of a groundwith known compactness characteristics on which a road surface (210) isspread, and equipped with a safety road barrier comprising a pluralityof uprights (110), fixed in the edge of the road as in the known art,and wherein said safety barrier comprises at least the elements: a. asystem of vertical plates (153), with a thin section, infixed on saidroad substrate (201) below said road surface (210); b. a junctionelement (151) arranged to be coupled to an upright (110) of a roadsafety barrier by wrapping them around its base; c. a connecting tie rod(152) lying, or slightly buried, on the road substrate (201), which is:i. coupled to said system of vertical plates (153) at one of its ends,and ii. releasably coupled to said junction element (151) at its otherend; and said junction element (151) comprises parts with programmedbreakage; and said programmed breakage is designed to happen when thefollowing conditions occur: said connecting tie rod (152) exerts atraction force on said junction element (151) higher than apredetermined threshold, and said connecting tie rod (152) exerts atraction force on said junction element (151) lower than the force thatwould damage said connecting tie rod (152) or to the force that wouldcause a displacement of said system of vertical plates (153) withrespect to the road substrate in which it is infixed.
 2. The roadaccording to claim 1 wherein said system of vertical plates (153) has across-shaped section.
 3. The road according to claim 1 wherein saidjunction element (151) comprises: c. a U-shaped element (151.1), thesize of which is suitable for “wrapping” said uprights (110) of a roadsafety barrier; d. a closing bar (151.3), arranged to close said“U”-shaped element (151.1), hooking at its two ends, so as to completelyenvelop an upright (110) of a road safety barrier; and said closing bar(151.3) has at least one hole (151.4), being the width of said hole(151.4) adjustable and correlated, by means of a known function, to thetraction force that must be exerted on said connecting tie rod (152) sothat said closing bar (151.3) breaks.
 4. The road according to claim 1wherein each upright (110) of a sequence of consecutive uprights (110),infixed in the roadside, is connected to at least two of said systems ofvertical plates 153, and each of said systems of vertical plates 153 isconnected to at least two uprights (110).
 5. The method of installing asafety road barrier for making a road according to claim 1 starting froma pre-existing road in which the roadway comprises a road substrate(201) and a road surface (210) made with an asphalt layer; and thisinstallation method includes at least the steps listed below: a. cuttingof the asphalt with which said road surface (210) is made i. accordingto the shape of the section of said system of vertical plates (153), andii. according to a line that connects the previous cut and the positionwhere the installation of a “guardrail” upright is planned; b. hookingsaid connecting tie rod (152) to said system of vertical plates (153)and laying it inside the cut referred to in point “ii.” above, so thatafter installation, said tie rod is laid on the road substrate (orslightly buried) below the level of the road surface; c. driving thesystem of vertical plates (153) by means of a pile-driving machine, sothat it is substantially buried entirely in the road substrate (201) orprotrudes from it for a very small part in comparison with the thicknessof the road surface (210) above; d. coupling said junction element (151)to the end of the connecting tie rod (152) which is located near thepoint where the upright (110) of a road safety barrier must be fixed; e.driving said upright (110) of a safety road barrier, by means of apile-driving machine so that said upright (110) slips into said junctionelement (151) remaining hooked to it; f. tensioning said connecting tierod (152) by means of a suitable maneuver performed on said joiningelement (151); g. sealing of the cuts made on the asphalt paving.
 6. Themethod for creating a road according to claim 1 starting from a road inwhich the roadway, composed of said road substrate (201) and said roadsurface (210), is pre-existing and said road is already equipped with asafety road barrier, installed by simple infixion of the uprights (110)into the ground at the edge of the road; and this manufacturing methodincludes at least the steps listed below: a. cutting of the asphalt withwhich said road surface is made (210) i. according to the shape of thesection of said system of vertical plates (153), and ii. according to aline that connects the previous cut and the position where the uprightof a “guardrail” is planted; b. hooking said connecting tie rod (152) tosaid system of vertical plates (153) and laying it inside the cutreferred to in point “ii.” above, so that after installation, said tierod is laid on the road substrate (or slightly buried) below the levelof the road surface; c. driving the system of vertical plates (153) bymeans of a pile-driving machine, so that it is substantially buriedentirely in the road substrate (201) or protrudes from it for a verysmall part in comparison with the thickness of the road surface (210)above; h. coupling said junction element (151) to an upright (110) ofthe road safety barrier with which said road is equipped; i. couplingsaid junction element (151) to the end of the connecting tie rod (152)which is located near the point where it is infixed the upright (110) ofthe safety road barrier, that is the same upright to which said junctionelement (151) had previously been coupled; j. tensioning said connectingtie rod (152) by means of a suitable maneuver performed on said joiningelement (151); k. sealing of the cuts made on the asphalt paving.
 7. Themethod according to claim 5 in which the asphalt cutting phase,indicated in both claims at point “a.”, is completed with an asphaltcore drilling operation aimed at removing small parts of the roadsurface (210) so as to be able to drive into the underlying roadsubstrate (201) also systems of vertical plates (153) which haveenlargements in their section.